# Re: Re: Density statistic calculation in case of histogram

From: Alberto Dell'Era <alberto.dellera_at_gmail.com>

Date: Thu, 9 Apr 2009 00:14:31 +0200

Message-ID: <4ef2fbf50904081514k347d2e8s6c3a155e8bb001db_at_mail.gmail.com>

On Mon, Apr 6, 2009 at 17:20, Neeraj Bhatia <neeraj.dba_at_gmail.com> wrote:

Date: Thu, 9 Apr 2009 00:14:31 +0200

Message-ID: <4ef2fbf50904081514k347d2e8s6c3a155e8bb001db_at_mail.gmail.com>

On Mon, Apr 6, 2009 at 17:20, Neeraj Bhatia <neeraj.dba_at_gmail.com> wrote:

*> Basically I am interested to know how density is calculated in case of**> height-based histograms. Also, how CBO calculate selectivity.*I wouldn't investigate too much the density in 10.x since the formula has changed (to a very intuitive one) in 11gR1:

http://www.adellera.it/investigations/11g_newdensity/index.html

so, the 10.x formula has been "deprecated" by the kernel developers.

I did find a statistical justification for the 10.x computation, but I have never "published" it for the above reasons, it is no longer important.

hth

alberto

-- http://www.freelists.org/webpage/oracle-lReceived on Wed Apr 08 2009 - 17:14:31 CDT